Methods and system for creating focal planes using an Alvarez lens

ABSTRACT

Configurations are disclosed for presenting virtual reality and augmented reality experiences to users. The system may comprise a lens assembly comprising two transmissive plates, a first of the two transmissive plates comprising a first surface sag based at least in part on a cubic function, and a DOE to direct image information to a user&#39;s eye; wherein the DOE is placed in between the two transmissive plates of the lens assembly, and wherein the DOE is encoded with the inverse of the cubic function corresponding to the surface sag of the first transmissive plate; such that a wavefront created by the encoded DOE is compensated by the wavefront created by the first transmissive plate, thereby collimating light rays associated with virtual content delivered to the DOE.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. patent application Ser. No.15/004,749, filed Jan. 22, 2016 entitled “METHODS AND SYSTEM FORCREATING FOCAL PLANES USING AN ALVAREZ LENS”, which claims priority toU.S. Provisional Application Ser. No. 62/106,391 filed on Jan. 22, 2015entitled “METHODS AND SYSTEM FOR CREATING FOCAL PLANES USING AN ALVAREZLENS,”. This application is cross-related to U.S. patent applicationSer. No. 14/726,429 filed on May 29, 2015 entitled “METHODS AND SYSTEMSFOR CREATING FOCAL PLANES IN VIRTUAL AND AUGMENTED REALITY,” and U.S.patent application Ser. No. 14/555,585 filed on Nov. 27, 2014 entitled“VIRTUAL AND AUGMENTED REALITY SYSTEMS AND METHODS,”. The contents ofthe aforementioned patent applications are hereby expressly and fullyincorporated by reference in their entirety for all purposes, as thoughset forth in full.

BACKGROUND

Modern computing and display technologies have facilitated thedevelopment of systems for so called “virtual reality” or “augmentedreality” experiences, wherein digitally reproduced images or portionsthereof are presented to a user in a manner wherein they seem to be, ormay be perceived as, real. A virtual reality, or “VR”, scenariotypically involves presentation of digital or virtual image informationwithout transparency to other actual real-world visual input; anaugmented reality, or “AR”, scenario typically involves presentation ofdigital or virtual image information as an augmentation to visualizationof the actual world around the user.

There are numerous challenges when it comes to presenting 3D virtualcontent to a user of an AR system. A central premise of presenting 3Dcontent to a user involves creating a perception of multiple depths. Inother words, it may be desirable that some virtual content appear closerto the user, while other virtual content appear to be coming fromfarther away. Thus, to achieve 3D perception, the AR system should beconfigured to deliver virtual content at different focal planes relativeto the user.

There may be many different ways to generate various focal planes in thecontext of AR systems. Some example approaches are provided in U.S.patent application Ser. No. 14/726,429 filed on May 29, 2015 entitled“METHODS AND SYSTEMS FOR CREATING FOCAL PLANES IN VIRTUAL AND AUGMENTEDREALITY,” and U.S. patent application Ser. No. 14/555,585 filed on Nov.27, 2014 entitled “VIRTUAL AND AUGMENTED REALITY SYSTEMS AND METHODS,”,incorporated by reference above. The design of these virtual realityand/or augmented reality systems presents numerous challenges, includingthe speed of the system in delivering virtual content, quality ofvirtual content, eye relief of the user, size and portability of thesystem, and other system and optical challenges.

The systems and techniques described herein are configured to work withthe visual configuration of the typical human to address thesechallenges.

SUMMARY

Embodiments of the present invention are directed to devices, systemsand methods for facilitating virtual reality and/or augmented realityinteraction for one or more users.

In one aspect, an augmented reality (AR) display system for deliveringaugmented reality content to a user is disclosed. The AR display systemcomprises an image-generating source to provide one or more frames ofimage data, a light modulator to transmit light associated with the oneor more frames of image data, a lens assembly comprising first andsecond transmissive plates, the first and second transmissive plateseach having a first side and a second side that is opposite to the firstside, the first side being a plano side, and the second side being ashaped side, the second side of the first transmissive plate comprisinga first surface sag based at least in part on a cubic function, and thesecond side of the second transmissive plate comprising a second surfacesag based at least in part on an inverse of the cubic function, and adiffractive optical element (DOE) to receive the light associated withthe one or more frames of image data and direct the light to the user'seyes, the DOE being disposed between and adjacent to the first side ofthe first transmissive plate and the first side of the secondtransmissive plate, and wherein the DOE is encoded with refractive lensinformation corresponding to the inverse of the cubic function such thatwhen the DOE is aligned such that the refractive lens information of theDOE cancels out the cubic function of the first transmissive plate, awavefront of the light created by DOE is compensated by the wavefrontcreated by the first transmissive plate, thereby generating collimatedlight rays associated with virtual content delivered to the DOE.

The AR system may further comprise an actuator to laterally translatethe DOE relative to the lens assembly, in one or more embodiments. Inone or more embodiments, the DOE is laterally translated in relation tothe lens assembly on a frame-to-frame basis. In one or more embodiments,the system further comprises

an eye tracking module to track a vergence of the user's eyes, whereinthe DOE is laterally translated relative to the lens assembly based atleast in part on the tracked vergence.

In one or more embodiments, the lateral displacement of the DOE causesthe light rays emanating from the DOE to appear to diverge from a depthplane, wherein the depth plane is not an infinite depth plane. In one ormore embodiments, collimated light rays appear to emanate from infinity.

In one or more embodiments, the second transmissive plate is placed inrelation to the first transmissive plate with their respective verticeson an optical axis such that light associated with outside worldobjects, when viewed by the user are perceived as having zero opticalpower. In one or more embodiments, the AR system further comprisesanother actuator to laterally translate the second transmissive plate inrelation to the first transmissive plate. In one or more embodiments,the second transmissive plate is laterally offset in a first directionin relation to the first transmissive plate such that light associatedwith outside world objects, when viewed by the user, is perceived ashaving a positive optical power.

In one or more embodiments, the second transmissive plate is laterallyoffset in a second direction in relation to the first transmissive platesuch that light associated with outside world objects, when viewed bythe user, is perceived as having a negative optical power. In one ormore embodiments, the image generating source delivers the one or moreframes of image data in a time-sequential manner.

In another aspect, a method of generating different focal planes isdisclosed. The method comprises delivering light associated with one ormore frames of image data to a diffractive optical element (DOE), theDOE disposed between a lens assembly comprising two transmissive plates,each of the transmissive plates having a first side and a second sidethat is opposite to the first side, the first side being a plano side,and the second side being a shaped side, the second side of the firsttransmissive plate comprising a first surface sag based at least in parton a cubic function, and the second side of the second transmissiveplate comprising a second surface sag based at least in part on aninverse of the cubic function, the DOE being disposed between andadjacent to the first side of the first transmissive plate and the firstside of the second transmissive plate, and wherein the DOE is encodedwith refractive lens information corresponding to the inverse of thecubic function such that when the DOE is aligned such that therefractive lens information of the DOE cancels out the cubic function ofthe first transmissive plate, a wavefront of the light created by DOE iscompensated by the wavefront created by the first transmissive plate,thereby generating collimated light rays associated with virtual contentdelivered to the DOE.

In one or more embodiments, the method further comprises laterallytranslating the DOE in relation to the first transmissive plate suchthat light rays associated with the virtual content delivered to the DOEdiverge at varying angles based at least in part on the lateraltranslation.

In one or more embodiments, the divergent light rays are perceived bythe user as coming from a depth plane other than optical infinity. Inone or more embodiments, the method further comprises tracking avergence of the user's eye, wherein the DOE is laterally translatedbased at least in part on the tracked vergence of the user's eyes.

In one or more embodiments, the second transmissive plate is placed inrelation to the DOE and the first transmissive plate such that outsideworld objects, when viewed by the user through the lens assembly and theDOE, are perceived through zero optical power. In one or moreembodiments, the second transmissive plate is offset in a firstdirection in relation to the DOE and the first transmissive plate suchthat outside world objects, when viewed by the user through the lensassembly and the DOE are perceived as having a positive optical power.

In one or more embodiments, the second transmissive plate is offset in asecond direction in relation to the DOE and the first transmissive platesuch that outside world objects, when viewed by the user through thelens assembly and the DOE are perceived as having a negative opticalpower. In one or more embodiments, the first direction is opposite tothe second direction.

In one or more embodiments, the collimated lights rays associated withthe virtual content appear to emanate from optical infinity. In one ormore embodiments, the method further comprises delivering one or moreframes of virtual content to the DOE in a time-sequential manner. In oneor more embodiments, the DOE is laterally translated in relation to thefirst transmissive plate on a frame-to-frame basis.

In one or more embodiments, the one or more frames of virtual contentdelivered to the DOE comprise two-dimensional image slices of one ormore three-dimensional objects.

In yet another aspect, an augmented reality display system comprises alens assembly comprising two transmissive plates of an Alvarez lens, afirst of the two transmissive plates comprising a first surface sagbased at least in part on a cubic function, and a second of the twotransmissive plates comprising a second surface sag based at least inpart on an inverse of the cubic function such that when the twotransmissive plates are disposed with their respective vertices on anoptical axis, an induced phase variation of the first transmissive plateis canceled out by the second transmissive plate, and a DOE to receiveand direct image information pertaining to virtual content to a user'seye, wherein the DOE is disposed between the first and secondtransmissive plates of the Alvarez lens, and wherein the DOE is encodedwith the inverse of the cubic function corresponding to the firstsurface sag of the first transmissive plate, such that, when the DOE isaligned with the first transmissive plate, a wavefront created by theencoded DOE is compensated by the wavefront created by the firsttransmissive plate, thereby collimating light rays associated withvirtual content delivered to the DOE.

In one or more embodiments, the DOE is laterally translated in relationto the first transmissive plate such that the light rays exiting thelens assembly are divergent. In one or more embodiments, the augmentedreality display system further comprises an eye tracking module to tracka vergence of the user's eyes, wherein the DOE is laterally translatedbased at least in part on the tracked vergence of the user's eyes.

In one or more embodiments, the divergent light rays appear to divergefrom a depth plane other than optical infinity. In one or moreembodiments, the collimated light rays appear to emanate from opticalinfinity.

In one or more embodiments, the second transmissive plate is placed inrelation to the first transmissive plate with their respective verticeson an optical axis such that light associated with outside worldobjects, when viewed by the user are perceived as having zero opticalpower. In one or more embodiments, the second transmissive plate isoffset in a first direction in relation to the first transmissive platesuch that light associated with outside world objects, when viewed bythe user, are perceived as having a positive optical power.

In one or more embodiments, the second transmissive plate is offset in asecond direction in relation to the first transmissive plate such thatlight associated with outside world objects, when viewed by the user,are perceived as having a negative optical power, wherein the seconddirection is opposite to the first direction.

In one or more embodiments, the augmented reality display system furthercomprises an image generating source, wherein the image generatingsource delivers one or more frames of image data in a time-sequentialmanner. In one or more embodiments, the DOE is laterally translated inrelation to the first transmissive plate on a frame-to-frame basis.

Additional and other objects, features, and advantages of the inventionare described in the detail description, figures and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate the design and utility of various embodiments ofthe present invention. It should be noted that the figures are not drawnto scale and that elements of similar structures or functions arerepresented by like reference numerals throughout the figures. In orderto better appreciate how to obtain the above-recited and otheradvantages and objects of various embodiments of the invention, a moredetailed description of the present inventions briefly described abovewill be rendered by reference to specific embodiments thereof, which areillustrated in the accompanying drawings. Understanding that thesedrawings depict only typical embodiments of the invention and are nottherefore to be considered limiting of its scope, the invention will bedescribed and explained with additional specificity and detail throughthe use of the accompanying drawings in which:

FIG. 1 illustrates a plan view of an Alvarez lens in three differentconfigurations.

FIG. 2 illustrates a plan view of a diffractive optical element (DOE)encoded with refractive lens information and one transmissive plate ofthe Alvarez lens.

FIG. 3 illustrates an example embodiment of light passing through anoptics assembly comprising the DOE and the Alvarez lens of FIG. 1.

FIG. 4 illustrates an example embodiment of varying depth planes usingthe optics assembly of FIG. 3.

FIGS. 5A-5C illustrate various configurations in which the DOE goesthrough different lateral translations in relation to the Alvarez lens.

FIG. 6 illustrates an example method of generating depth planes usingthe optics assembly of FIG. 3.

FIG. 7 illustrates an example embodiment of modifying the opticsassembly of FIG. 3 to compensate for a user's optical prescription.

FIG. 8 illustrates a plan view of an example configuration of a systemutilizing the optics assembly of FIG. 3.

DETAILED DESCRIPTION

Various embodiments of the invention are directed to methods, systems,and articles of manufacture for implementing multi-scenariophysically-aware design of an electronic circuit design in a singleembodiment or in some embodiments. Other objects, features, andadvantages of the invention are described in the detailed description,figures, and claims.

Various embodiments will now be described in detail with reference tothe drawings, which are provided as illustrative examples of theinvention so as to enable those skilled in the art to practice theinvention. Notably, the figures and the examples below are not meant tolimit the scope of the present invention. Where certain elements of thepresent invention may be partially or fully implemented using knowncomponents (or methods or processes), only those portions of such knowncomponents (or methods or processes) that are necessary for anunderstanding of the present invention will be described, and thedetailed descriptions of other portions of such known components (ormethods or processes) will be omitted so as not to obscure theinvention. Further, various embodiments encompass present and futureknown equivalents to the components referred to herein by way ofillustration.

Disclosed are methods and systems for generating virtual and/oraugmented reality. In order to provide a realistic and enjoyable virtualreality (VR) or augmented reality (AR) experience, virtual contentshould be presented at varying depths away from the user such that thevirtual content is perceived to be realistically placed or originatingfrom a real-world depth (in contrast to traditional 2D displays). Thisapproach closely mimics the real world experience of sight, in that theeyes constantly change focus in order to view different objects atdifferent depths. For example, muscles of the human eye “tighten” inorder to focus on a nearby object, and “relax” in order to focus on anobject that is farther away.

By placing virtual content in a manner that closely mimics real objects,the user's natural physiological response (e.g., different focus fordifferent objects) remains substantially intact, thereby providing amore realistic and comfortable viewing experience. This is in contrastto traditional VR or AR systems that force the user to view virtualcontent on a fixed depth plane (e.g., 2D screen like Google Glass® orOculus®), forcing the user to go back and forth between real objects ofthe real world and the virtual content, which causes discomfort to theuser. The present application discusses various AR system approaches toproject 3D virtual content such that it is perceived at varying depthsby the user.

In order to present 3D virtual content to the user, the augmentedreality (AR) system projects images of the virtual content at varyingdepth planes in the z direction from the user's eyes. In other words,the virtual content presented to the user not only changes in the x andy direction (as is the case with most 2D content), but it may alsochange in the z direction, giving a perception of 3D depth. Thus, theuser may perceive a virtual object to be very close (e.g., a virtualbook placed on a real desk) or at an infinite distance (e.g., a virtualtree at a very large distance away from the user) or any distance inbetween. Or, the user may perceive multiple objects simultaneously atdifferent depth planes. For example, the user may see a virtual dragonappear from infinity and running towards the user. In anotherembodiment, the user may simultaneously see a virtual bird at a distanceof 1 meter away from the user and a virtual coffee cup at arm's lengthfrom the user.

There may be two main ways of creating a perception of variable depth:multiple-plane focus systems and variable plane focus systems. In amultiple-plane focus system, the system is configured to project virtualcontent on fixed depth planes in the z direction away from the user. Ina variable plane focus system, the system projects one or more depthplanes, but moves the depth plane(s) in the z direction to create 3Dperception. In one or more embodiments, a variable focus element (VFE)may be utilized to change the focus of light associated with virtualcontent, such that the light appears to be coming from a particulardepth. In other embodiments, hardware components corresponding todifferent foci may be strategically employed to create a perception ofmultiple depth planes, as will be discussed in further detail below. TheVFE may vary the focus of the light on a frame-by-frame basis. Moredetails on various types of multiple-plane and variable plane focussystems may be found in U.S. application Ser. No. 14/726,429, entitled“METHODS AND SYSTEMS FOR CREATING FOCAL PLANES IN VIRTUAL AND AUGMENTEDREALITY” and filed on May 29, 2015, which was incorporated by referenceabove for all purposes.

In one embodiment of a multiple-plane focal system, various focal planesare generated through the user of diffractive optical elements (DOE)(e.g., volume phase holograms, surface relief diffractive elements,etc.) that are encoded with depth plane information. In one or moreembodiments, a DOE refers to a physical light guiding optical elementencoded with a light guiding pattern.

In this approach, a wavefront may be encoded within the DOE such thatwhen a collimated beam is totally internally reflected along the DOE, itintersects the wavefront at multiple locations. To explain, collimatedlight associated with one or more virtual objects is fed into the DOEwhich acts as a light guide. Due to the wavefront or refractive lensinformation that is encoded into the DOE, the light that is totallyinternally reflected within the DOE will intersect the DOE structure atmultiple points, and diffract outwards toward the user through the DOE.In other words, the light associated with the one or more virtualobjects is transformed based on the encoded refractive lens informationof the DOE. Thus, it can be appreciated that different wavefronts may beencoded within the DOE to create different diffraction patterns forlight rays that are fed into the DOE. A first DOE may have a firstwavefront that produces a first divergence angle for light rays exitingthe DOE. This may cause the user to perceive any delivered virtualcontent at a first depth plane. Similarly, a second DOE may have asecond wavefront that produces a second divergence angle for light raysexiting the DOE. This may cause the user to perceive the deliveredvirtual content at a second depth plane. In yet another example, a DOEmay be encoded with a wavefront such that it delivers collimated lightto the eye. Since the human eye perceives collimated light as lightcoming from infinity, this DOE may represent the infinity plane.

As discussed above, this property of DOEs that are encoded withdifferent wavefronts may be used to create various depth planes whenperceived by the eye. For example, a DOE may be encoded with a wavefrontthat is representative of a 0.5 meter depth plane such that the userperceives the virtual object to be coming from a distance of 0.5 metersaway from the user. Another DOE may be encoded with a wavefront that isrepresentative of a 3 meter depth plane such that the user perceives thevirtual object to be coming from a distance of 3 meters away from theuser. By using a stacked DOE assembly, it can be appreciated thatmultiple depth planes delivering different virtual content may becreated for the AR experience, with each DOE configured to displayvirtual images at a respective depth plane. In one embodiment, sixstacked DOEs may be used to generate six depth planes.

It should be appreciated that the stacked DOEs may be further configuredto be dynamic, such that one or more DOEs may be turned on or off. Inone embodiment, one or more DOEs are switchable between “on” states inwhich they actively diffract, and “off” states in which they do notsignificantly diffract. For instance, a switchable DOE may comprise alayer of polymer dispersed liquid crystal, in which microdropletscomprise a wavefront in a host medium, and the refractive index of themicrodroplets can be switched to substantially match the refractiveindex of the host material (in which case the wavefront does notappreciably diffract incident light) or the microdroplet can be switchedto an index that does not match that of the host medium (in which casethe wavefront actively diffracts incident light). More details on DOEsare described in U.S. patent application Ser. No. 14/555,585 filed onNov. 27, 2014 and entitled “VIRTUAL AND AUGMENTED REALITY SYSTEMS ANDMETHODS”, incorporated by reference above for all purposes.

In one or more embodiments, the stacked DOE assembly system may becoupled with an eye-tracking sub-system. The eye-tracking sub-systemcomprises a set of hardware and software components that is configuredto track a movement of the user's eyes to determine that user's currentpoint (and depth) of focus. Any type of eye-tracking sub-system may beused. For example, one example eye-tracking system tracks a vergence ofthe user's eyes to determine a user's current depth of focus. Othereye-tracking sub-systems may user other suitable methods. Thisinformation pertaining to the user's current state of focus may, inturn, be used to determine which of the multiple DOEs should be turnedon or off at any given point in time. For example, if it is determinedthat the user is currently looking at an object that is 3 meters away,one or more DOEs that are configured to display virtual content at (oraround) 3 meters may be turned off, while the remaining DOEs are turnedoff. It should be appreciated that the above configurations are exampleapproaches only, and other configurations of the stacked DOE system maybe similarly used.

Although the stacked DOE assembly is effective in creating differentdepth planes at fixed distances away from the user (e.g., ⅓ diopter, ½diopter, optical infinity, etc.), it may be somewhat bulky for some ARapplications. Although any number of DOEs may be stacked to create thestacked DOE assembly, typically at least six DOEs are stacked togetherto give the user an illusion of full 3D depth. Thus, this may give thesystem a rather bulky look rather than a look of a sleek optical system.Also, stacking multiple DOEs together adds to the overall weight of theAR system.

Moreover, it should be appreciated that this type of multiple focalplane system generates fixed depth planes at fixed distances away fromthe user. For example, as described above, a first depth plane may begenerated at ⅓ diopter away from the user, a second may be generated at½ diopter away, etc. While this arrangement may be configured such thatit is accurate enough when turning on the right depth plane based on theuser's focus, it can be appreciated that the user's eyes still have toslightly change focus to the fixed depth plane projected by the system.

To explain, let's assume that the stacked DOE system comprises 6 stackedDOEs (e.g., ⅓ diopter, ½ diopter, 1 diopter, 2 diopters, 4 diopters andoptical infinity), and the user's eyes are focused at a distance of 1.1diopters. Based on input received through the eye-tracking system, thethird DOE element (1 diopter) may be switched on, and virtual contentmay be delivered at a depth of 1 diopter away. This requires the user tosubtly change focus from his/her original focus of 1.1 diopter to 1diopter to appreciate the virtual content being delivered. Thus, ratherthan creating a depth plane at 1.1 diopters, which coincides with theuser's focus, the system forces the user to slightly change focus to thedepth plane created by the system. This may produce some discomfort tothe user. The following disclosure presents methods and systems to useDOEs in a variable plane focus system rather than a multi-plane focussystem, such that only a single depth plane is created to coincide withthe vergence of the user's eyes (detected by the eye-tracking subsystem). Additionally, using a single DOE instead of six may make thesystem less bulky and more aesthetically pleasing. Further, in somesystems that utilize multiple fixed depth planes, it may be difficult totransition from one depth plane to another depth plane when projecting amoving virtual object. It may be difficult to handle the transitioningof one depth plane to another (e.g., an object moving closer to theuser) more seamlessly through a system that continuously adjusts thedepth of the virtual object rather than jumps from one fixed depth planeto another fixed depth plane.

To this end, a single DOE encoded with depth information may be coupledto an Alvarez lens, as will be described further below. An Alvarez lenscomprises two transmissive refractive plates, each of the twotransmissive plates having a plano surface and a surface shaped in atwo-dimensional cubic profile (e.g., surface sag). The plano surface maybe a substantially flat surface, in one or more embodiments. Typically,the two cubic surfaces are made to be the inverse of each other suchthat when both transmissive plates are placed with their respectivevertices on the optical axis, the phase variations induced by the twotransmissive plates cancel each other out. The phase contours of theAlvarez lens typically result from a cubic function or polynomialfunction similar to S=a(y³+3x²y). S represents the surface sag of theAlvarez lens. It should be appreciated that the actual cubic functionmay be different based on the application for which the Alvarez lens isdesigned. For example, depending on the nature of the AR application(e.g., number of depth planes, type of depth planes, type of virtualcontent, etc.), the actual mathematical function with which the surfacesag of the transmissive plates is created may be changed. For example,the “a” in the equation above may be different for different types of ARdevices. Similarly, any of the other variables of the equation above maybe changed as well. In one or more embodiments, the surface sag of theAlvarez lens is based on a cubic function in one direction, and the x²yfunction in the other direction. With the transmissive plates createdusing this combined mathematical function, the transmissive plates areable to be focused in both directions.

Further, the surface sag may also be created using mathematical terms inaddition to the main mathematical equation described above. Theadditional sag terms may take the form of Ax²+By²+Cy³, etc. Theseadditional functions may help optimize the surface sag for ray tracingoptimization. Ray tracing optimization is used to adjust thecoefficients until a better outcome is obtained. It should beappreciated that these terms may create small perturbations on the basicsurface sag of the Alvarez lens, but could result in better performancefor AR purposes.

Referring now to the configurations 100 shown in FIG. 1, as discussedbriefly above, when the two plates of the Alvarez lens are placed suchthat their vertices are on the optical axis (102), the induced phasevariations cancel each other out, thereby making the Alvarez lens havezero power. In other words, if a user were to look through the Alvarezlens in a configuration such as that depicted in 102, the user wouldsimply see through the lens as if looking through a transparent piece ofglass.

However, if the two transmissive plates undergo a relative lateraltranslation, such as that shown in 104 or 106, a phase variation isinduced, resulting in either negative power (104) or positive power(106). The resulting phase variation is the differential of the cubicsurface profiles, resulting in a quadratic phase profile, or opticalpower. As shown in FIG. 1, the optical power may either be positivepower or negative power. It can be appreciated that the magnitude of thepower may vary based on the cubic function corresponding to the contoursof the Alvarez Lens, as discussed above.

In one embodiment, the Alvarez lens is coupled to a single DOE (e.g.,volumetric phase grating, surface relief DOE, etc.) such that theassembly as a whole helps create multiple depth planes for presentingvirtual content in 3D to the user. More particularly, rather thanencoding a particular depth plane information (i.e., refractive lensinformation) in the DOE, it is instead encoded with a cubic function(e.g., inverse of the cubic function of a transmissive plate of theAlvarez lens) that compensates for the wavefront on one of the plates ofthe Alvarez lens. Thus, rather than moving the plates of the Alvarezlens relative to each other, the DOE can be moved relative to bothplates of the Alvarez lens to produce different depth planes for theuser.

Referring now to the Alvarez lens configuration 200 of FIG. 2, the DOEcan be encoded with the inverse of the cubic function of one of theplates of the Alvarez lens, such that it compensates for the refractivelens function of one of the transmissive plates of the Alvarez lens. Inthe illustrated embodiment, the DOE 202 is encoded such that the lightassociated with the delivered virtual content exits the DOE 202 in amanner than mimics the inverse of the wavefront of one of thetransmissive plates of the Alvarez lens. For illustrative purposes, asshown in FIG. 2, the light exiting the DOE 202 is shown to come out in apattern, rather than all coming out straight, for example. In theillustrated embodiment, the light exiting one of the transmissive plates204 is shown to be coming out in a manner that is the opposite of thepattern of light exiting the DOE 202. Since the two patterns constitutemathematical inverses of each other, putting the two patterns togethercancels the two resulting wavefronts out such that the light reachingthe eye of the user is collimated (e.g., is perceived as coming frominfinity. It should be appreciated that the other transmissive plate ofthe Alvarez lens ensures that the user views a non-distorted image ofthe desired virtual content such that light from the outside worldreaches the user's eye in a non-distorted manner.

In the configuration 300 of the Alvarez lens shown in FIG. 3, the lightrays exiting the assembly of the DOE 202 and one of the transmissiveplate 204 appear to be collimated rather than having a diverging patternas shown in FIG. 2 because the wavefront generated by the DOE 202cancels out the inverse wavefront generated by the transmissive plate204 and vice versa. Thus, as shown in FIG. 3, the light exiting thecombination of the DOE 202 and the transmissive plate 204 is collimated.Since collimated light rays are perceived by the eye as light rayscoming from infinity, the user perceives the virtual content as comingfrom the infinity depth plane.

It should be appreciated that the other transmissive plate 304 is alsoan integral part of the assembly since it cancels out the wavefront ofthe transmissive plate 204. Thus, light from the world passes throughthe refractive pattern of the transmissive plate 304 and is canceled outby the inverse wavefront of the other transmissive plate 204 such thatwhen the user looks through the assembly, he or she views light comingfrom the world as is, at zero power, as discussed in relation to FIG. 1.As discussed above, the light passing through from the world isunaffected by the DOE, and when the transmissive plates are perfectlyaligned, the Alvarez lens is substantially transparent.

In one or more embodiments, the lens assembly and the DOE may furthercomprise a marking mechanism to denote that the DOE is perfectly alignedwith the lens assembly constituting the Alvarez lens such thatcollimated light is generated. For example, the marking mechanism maysimply be a demarcation on the DOE that indicates that the alignment ofthe demarcation of the DOE with the Alvarez lens (or correspondingmarkings of the Alvarez lens) will product cancellation of the wavefront(e.g., collimation of light). Similarly, the AR system may detect (e.g.,through a sensor, an electromechanical switch, etc.) that the DOE isperfectly aligned with the Alvarez lens through any other suitablemechanism.

Referring back to FIG. 3, and as discussed above, the user views thedelivered virtual content at the infinity depth plane (i.e., the lightrays reaching the eye are collimated). Thus, if the user's eyes arefocused at infinity (as detected by the eye-tracking sub system of theAR device), the optics configuration of FIG. 3 would be effective inprojecting light as though coming from the infinity depth plane.However, to project virtual content as though coming from other depthplanes, light coming from the optics assembly has to be modified suchthat it diverges at a desired depth plane.

To that end, the DOE 202 may be laterally translated in relation to thetransmissive plates of the Alvarez lens to produce diverging light raysthat diverge at a desired depth plane. Referring now to FIG. 4, at 402,the light rays from the world and the light rays associated with thevirtual content are both collimated when reaching the eye. Thus, asdiscussed above, the user perceives the virtual content as though comingfrom an infinite depth plane. To create this effect, the twotransmissive plates 304 and 204 of the Alvarez lens are placed such thatthey exactly cancel out their respective wavefronts and light from theworld appears as is (i.e., zero power), and the DOE 202 is placeddirectly adjacent to the transmissive plate 204 such that the encodedwavefront of the DOE 202 and the wavefront of the transmissive plate 204cancel each other out also, thereby producing collimated light of thevirtual content that is perceived by the eye to be coming from infinity.Of course it should be appreciated that the placement of the DOE 202relative to the Alvarez lens has to be precise to create the effectabove.

At 404, the DOE 202 is moved laterally to the right relative to theAlvarez lens, thereby changing the wavefront of the outcoupled lightrays associated with the virtual content. Since transmissive plates 304and 204 are still aligned with one another, the user still views objectsof the outside world at zero power, but the virtual content is vieweddifferently, as will be described now. Rather than being collimated, aswas the case in 402, the light rays associated with the virtual contentfed into the DOE 202 are now divergent. The divergent light rays areperceived by the eye as coming from a particular depth plane. Thus, thedelivered virtual content may be perceived to be coming from a distanceof 3 meters, or 1.5 meters, or 0.5 meters, depending on the lateraltranslation of the DOE 202 relative to the transmissive plates 304 and204 of the Alvarez lens. For example, a slight lateral translation of0.5 mm may produce divergent light rays such that the virtual contentappears to be coming from a distance of 3 meters. Or, in anotherexample, a lateral translation of 1 mm may produce divergent light rayssuch that the virtual content appears to be coming from a distance of 2meters (example only). Thus, it can be appreciated that by moving theDOE 202 relative to the Alvarez lens, light rays associated with thevirtual content can be manipulated such that they appear to be comingfrom a desired depth plane.

FIGS. 5A-5C illustrate one embodiment of creating multiple depth planesproduced by lateral translation of the DOE 202 relative to the Alvarezlens. It should be appreciated that the other transmissive plate 304illustrated in FIGS. 3 and 4 are omitted in FIGS. 5A-5C solely forillustrative purposes. Other embodiments comprise both transmissiveplates of the Alvarez lens such that the DOE 202 is moved relative toboth of them.

Referring first to FIG. 5A, at 502, there is zero lateral shift betweenthe DOE 202 and the transmissive plate 204. As shown in FIG. 5A, sincethere is zero lateral shift between the DOE 202 and the transmissiveplate 204, the wavefront of the DOE is completely compensated by thewavefront of the transmissive plate 204, thereby resulting in collimatedlight reaching the user's eyes. As discussed extensively above, thisresults in the virtual content being perceived as coming from theinfinite depth plane.

Referring now to FIG. 5B, at 504, the DOE 202 is laterally translated(e.g., through an actuator, or any electro-mechanical means) in relationto the Alvarez lens by a lateral shift of 0.5 mm. As a result, the lightrays coming out of the optical assembly are not collimated, but ratherdiverge at a particular angle of divergence when reaching the user'seyes. Thus, the projected virtual content, when viewed by the user, doesnot appear to be coming from the infinity plane, but rather appears tobe coming from a finite depth plane (e.g., 5 ft. away from the user,etc.).

Referring now to FIG. 5C, at 506, the DOE 202 is further laterallytranslated in relation to the Alvarez lens by a shift of 1 mm. As aresult, the light rays coming out of the optical assembly have yetanother angle of divergence such that the projected virtual content,when viewed by the user, appears to be coming from another finite depthplane (e.g., 2 ft. away from the user, etc.). Thus, it can beappreciated that moving the DOE 202 in relation to the Alvarez lenshelps create multiple depth planes at which to project the desiredvirtual content.

Referring now to FIG. 6, an example method 600 of creating differentfocal planes using the optics assembly of FIG. 3 is described. It shouldbe appreciated that the optics assembly of FIG. 3 is part of a largeraugmented reality (AR) system that contains other sub-systems (e.g.,eye-tracking sub-system, fiber scan display (FSD), image processor, andother control circuitry).

At 602, the AR system determines, through the eye-tracking sub-system, avergence of the user's eyes. The user's eye vergence may be used todetermine where the user's eyes are currently focused. For purposes ofaccommodation and comfort to the user's eyes, the AR system projects thedesired virtual content where the user's eyes are already focused ratherthan forcing the user to change focus to view the virtual content. Thisprovides for a more comfortable viewing of the virtual content. Thedetermined vergence of the user's eyes dictates a focal distance orfocal depth at which to project one or more virtual content to the user.

At 604, the particular virtual content that is to appear in focus at thedetermined accommodation of the user's eyes is determined. For example,if the user is focused at infinity, it may be determined that a virtualcontent (e.g., a virtual tree) should appear in focus to the user. Theremaining portions of the virtual scene may be blurred through softwareblurring. Or, it may be determined that the entire set of virtualobjects should appear in focus based on the determined accommodation. Inthat case, all the virtual objects may be prepared for projection to theuser.

At 606, the AR system (e.g., through a processor) determines the lateralshift required (i.e., required lateral translation between the DOE 202and the Alvarez lens) to produce a depth plane at the determined focaldistance. This may be performed by searching through a mapping tablethat stores a correlation between a required lateral shift to effectuatea particular depth plane. Similarly, other such techniques may besimilar used.

At 608, based on the determined lateral shift, the DOE 202 is movedrelative to the transmissive plates of the Alvarez lens. It should beappreciated that the optics assembly may include a piezo actuator or avoice coil motor (VCM) that physically causes the lateral translation tothe desired shift (e.g., 0.5 mm, 1 mm, etc.). In one or moreembodiments, a plurality of actuators may be used to shift the DOE withrespect to the transmissive plates of the Alvarez lens. In someembodiments, a second actuator may be used to laterally shift onetransmissive plate of the Alvarez lens in relation to the othertransmissive plate of the Alvarez lens.

At 610, once the lateral shift is completed, virtual content isdelivered to the DOE 202. As discussed above, the lateral shift betweenthe DOE and the Alvarez lens produces divergence of the light rays suchthat the eye perceives the light associated with the virtual content tobe coming from a particular depth plane. Or if the user's eyes arefocused at infinity, the AR system would align the DOE 202 preciselywith the transmissive plates of the Alvarez lens such that theoutcoupled light rays are collimated, and the user perceives the lightassociated with the virtual content as coming from the infinite depthplane. In one embodiment, the virtual content may be fed into the DOEthrough a fiber scanner display (FSD), a DLP or any other type ofspatial light modulator.

Moreover, in yet another application of the Alvarez lens, thetransmissive plates may be oriented in a manner that compensates for theuser's current optical prescription. To explain, many users of the ARsystem may have some sort of prescription power that requires them towear prescription eye glasses or contacts. It may be difficult to wearthe AR system on top of eye glasses, or contacts. Thus, the Alvarez lensmay be used with the AR system that also compensates for the user'snear-sightedness (or far-sightedness) in addition to presenting virtualcontent at varying depth planes.

Referring back to FIG. 1, and as discussed above, when the twotransmissive plates are precisely aligned such that the wavefronts arecanceled out, the Alvarez lens has zero power. However, lateraltranslation of the transmissive plates relative to each other results ineither positive or negative power. This can be used in the context ofcompensation for prescription optical power of users. For example, if auser is near-sighted, the AR system may be designed such that thetransmissive plates of the Alvarez lens are slightly offset in relationto each other rather than being perfectly aligned, as was the case inprevious example.

In the illustrated embodiment 700 of FIG. 7, rather than being perfectlyaligned with each other, as was the case in the examples above, thetransmissive plates 304 and 204 are slightly offset, resulting innegative power. Of course, the magnitude of the shift between the platesmay be dictated by the user's prescription optical power. For example, alarger shift (or vice versa) may be required for a user having a largerprescription power. Or, a smaller shift (or vice versa) may besufficient for a user having a smaller prescription power. Given thatthe optical prescription power is the same, the AR system may be customdesigned for each user to compensate for the optical power so that theAR system can be comfortably worn without having to wear additional eyeglasses or contacts.

The lateral shift between the transmissive plates may remain constant,in one embodiment. Of course, it should be appreciated that the DOE 202also moves in relation with the offset transmissive plates as discussedabove. Thus, the lateral shift of the DOE 202 in relation to the Alvarezlens creates depth planes at varying distances, and the lateral shift ofthe transmissive plates of the Alvarez lens creates optical power tocompensate for a user's prescription optical power (e.g., nearsightedness, far sightedness, etc.)

Referring now to FIG. 8, an example embodiment 800 of the AR system thatuses a DOE in combination with the Alvarez lens will now be described.The AR system generally includes an image generating processor 812, atleast one FSD 808, FSD circuitry 810, a coupling optic 832, and at leastone optics assembly that includes the DOE and the transmissive plates ofthe Alvarez lens 802. The system may also include an eye-trackingsubsystem 808.

As shown in FIG. 8, the FSD circuitry may comprise circuitry 810 that isin communication with the image generation processor 812, a maxim chip818, a temperature sensor 820, a piezo-electrical drive/transducer 822,a red laser 826, a blue laser 828, and a green laser 830 and a fibercombiner that combines all three lasers 826, 828 and 830.

The image generating processor is responsible for generating virtualcontent to be ultimately displayed to the user. The image generatingprocessor may convert an image or video associated with the virtualcontent to a format that can be projected to the user in 3D. Forexample, in generating 3D content, the virtual content may need to beformatted such that portions of a particular image are displayed on aparticular depth plane while other are displayed at other depth planes.Or, all of the image may be generated at a particular depth plane. Or,the image generating processor may be programmed to feed slightlydifferent images to right and left eye such that when viewed together,the virtual content appears coherent and comfortable to the user's eyes.In one or more embodiments, the image generating processor 812 deliversvirtual content to the optics assembly in a time-sequential manner. Afirst portion of a virtual scene may be delivered first, such that theoptics assembly projects the first portion at a first depth plane. Then,the image generating processor 812 may deliver another portion of thesame virtual scene such that the optics assembly projects the secondportion at a second depth plane and so on. Here, the Alvarez lensassembly may be laterally translated quickly enough to produce multiplelateral translations (corresponding to multiple depth planes) on aframe-to frame basis.

The image generating processor 812 may further include a memory 814, aCPU 818, a GPU 816, and other circuitry for image generation andprocessing. The image generating processor may be programmed with thedesired virtual content to be presented to the user of the AR system. Itshould be appreciated that in some embodiments, the image generatingprocessor may be housed in the wearable AR system. In other embodiments,the image generating processor and other circuitry may be housed in abelt pack that is coupled to the wearable optics.

The AR system also includes coupling optics 832 to direct the light fromthe FSD to the optics assembly 802. The coupling optics 832 may refer toone more conventional lenses that are used to direct the light into theDOE assembly. The AR system also includes the eye-tracking subsystem 806that is configured to track the user's eyes and determine the user'sfocus.

In one or more embodiments, software blurring may be used to induceblurring as part of a virtual scene. A blurring module may be part ofthe processing circuitry in one or more embodiments. The blurring modulemay blur portions of one or more frames of image data being fed into theDOE. In such an embodiment, the blurring module may blur out parts ofthe frame that are not meant to be rendered at a particular depth frame.

In the foregoing specification, the invention has been described withreference to specific embodiments thereof. It will, however, be evidentthat various modifications and changes may be made thereto withoutdeparting from the broader spirit and scope of the invention. Forexample, the above-described process flows are described with referenceto a particular ordering of process actions. However, the ordering ofmany of the described process actions may be changed without affectingthe scope or operation of the invention. The specification and drawingsare, accordingly, to be regarded in an illustrative rather thanrestrictive sense.

Various example embodiments of the invention are described herein.Reference is made to these examples in a non-limiting sense. They areprovided to illustrate more broadly applicable aspects of the invention.Various changes may be made to the invention described and equivalentsmay be substituted without departing from the true spirit and scope ofthe invention. In addition, many modifications may be made to adapt aparticular situation, material, composition of matter, process, processact(s) or step(s) to the objective(s), spirit or scope of the presentinvention. Further, as will be appreciated by those with skill in theart that each of the individual variations described and illustratedherein has discrete components and features which may be readilyseparated from or combined with the features of any of the other severalembodiments without departing from the scope or spirit of the presentinventions. All such modifications are intended to be within the scopeof claims associated with this disclosure.

The invention includes methods that may be performed using the subjectdevices. The methods may comprise the act of providing such a suitabledevice. Such provision may be performed by the end user. In other words,the “providing” act merely requires the end user obtain, access,approach, position, set-up, activate, power-up or otherwise act toprovide the requisite device in the subject method. Methods recitedherein may be carried out in any order of the recited events which islogically possible, as well as in the recited order of events.

Example aspects of the invention, together with details regardingmaterial selection and manufacture have been set forth above. As forother details of the present invention, these may be appreciated inconnection with the above-referenced patents and publications as well asgenerally known or appreciated by those with skill in the art. The samemay hold true with respect to method-based aspects of the invention interms of additional acts as commonly or logically employed.

In addition, though the invention has been described in reference toseveral examples optionally incorporating various features, theinvention is not to be limited to that which is described or indicatedas contemplated with respect to each variation of the invention. Variouschanges may be made to the invention described and equivalents (whetherrecited herein or not included for the sake of some brevity) may besubstituted without departing from the true spirit and scope of theinvention. In addition, where a range of values is provided, it isunderstood that every intervening value, between the upper and lowerlimit of that range and any other stated or intervening value in thatstated range, is encompassed within the invention.

Also, it is contemplated that any optional feature of the inventivevariations described may be set forth and claimed independently, or incombination with any one or more of the features described herein.Reference to a singular item, includes the possibility that there areplural of the same items present. More specifically, as used herein andin claims associated hereto, the singular forms “a,” “an,” “said,” and“the” include plural referents unless the specifically stated otherwise.In other words, use of the articles allow for “at least one” of thesubject item in the description above as well as claims associated withthis disclosure. It is further noted that such claims may be drafted toexclude any optional element. As such, this statement is intended toserve as antecedent basis for use of such exclusive terminology as“solely,” “only” and the like in connection with the recitation of claimelements, or use of a “negative” limitation.

Without the use of such exclusive terminology, the term “comprising” inclaims associated with this disclosure shall allow for the inclusion ofany additional element—irrespective of whether a given number ofelements are enumerated in such claims, or the addition of a featurecould be regarded as transforming the nature of an element set forth insuch claims. Except as specifically defined herein, all technical andscientific terms used herein are to be given as broad a commonlyunderstood meaning as possible while maintaining claim validity.

The breadth of the present invention is not to be limited to theexamples provided and/or the subject specification, but rather only bythe scope of claim language associated with this disclosure.

The above description of illustrated embodiments is not intended to beexhaustive or to limit the embodiments to the precise forms disclosed.Although specific embodiments of and examples are described herein forillustrative purposes, various equivalent modifications can be madewithout departing from the spirit and scope of the disclosure, as willbe recognized by those skilled in the relevant art. The teachingsprovided herein of the various embodiments can be applied to otherdevices that implement virtual or AR or hybrid systems and/or whichemploy user interfaces, not necessarily the example AR systems generallydescribed above.

For instance, the foregoing detailed description has set forth variousembodiments of the devices and/or processes via the use of blockdiagrams, schematics, and examples. Insofar as such block diagrams,schematics, and examples contain one or more functions and/oroperations, it will be understood by those skilled in the art that eachfunction and/or operation within such block diagrams, flowcharts, orexamples can be implemented, individually and/or collectively, by a widerange of hardware, software, firmware, or virtually any combinationthereof.

In one embodiment, the present subject matter may be implemented viaApplication Specific Integrated Circuits (ASICs). However, those skilledin the art will recognize that the embodiments disclosed herein, inwhole or in part, can be equivalently implemented in standard integratedcircuits, as one or more computer programs executed by one or morecomputers (e.g., as one or more programs running on one or more computersystems), as one or more programs executed by on one or more controllers(e.g., microcontrollers) as one or more programs executed by one or moreprocessors (e.g., microprocessors), as firmware, or as virtually anycombination thereof, and that designing the circuitry and/or writing thecode for the software and or firmware would be well within the skill ofone of ordinary skill in the art in light of the teachings of thisdisclosure.

When logic is implemented as software and stored in memory, logic orinformation can be stored on any computer-readable medium for use by orin connection with any processor-related system or method. In thecontext of this disclosure, a memory is a computer-readable medium thatis an electronic, magnetic, optical, or other physical device or meansthat contains or stores a computer and/or processor program. Logicand/or the information can be embodied in any computer-readable mediumfor use by or in connection with an instruction execution system,apparatus, or device, such as a computer-based system,processor-containing system, or other system that can fetch theinstructions from the instruction execution system, apparatus, or deviceand execute the instructions associated with logic and/or information.

In the context of this specification, a “computer-readable medium” canbe any element that can store the program associated with logic and/orinformation for use by or in connection with the instruction executionsystem, apparatus, and/or device. The computer-readable medium can be,for example, but is not limited to, an electronic, magnetic, optical,electromagnetic, infrared, or semiconductor system, apparatus or device.More specific examples (a non-exhaustive list) of the computer readablemedium would include the following: a portable computer diskette(magnetic, compact flash card, secure digital, or the like), a randomaccess memory (RAM), a read-only memory (ROM), an erasable programmableread-only memory (EPROM, EEPROM, or Flash memory), a portable compactdisc read-only memory (CDROM), digital tape, and other nontransitorymedia.

Many of the methods described herein can be performed with variations.For example, many of the methods may include additional acts, omit someacts, and/or perform acts in a different order than as illustrated ordescribed.

The various embodiments described above can be combined to providefurther embodiments. To the extent that they are not inconsistent withthe specific teachings and definitions herein, all of the U.S. patents,U.S. patent application publications, U.S. patent applications, foreignpatents, foreign patent applications and non-patent publicationsreferred to in this specification and/or listed in the Application DataSheet. Aspects of the embodiments can be modified, if necessary, toemploy systems, circuits and concepts of the various patents,applications and publications to provide yet further embodiments.

These and other changes can be made to the embodiments in light of theabove-detailed description. In general, in the following claims, theterms used should not be construed to limit the claims to the specificembodiments disclosed in the specification and the claims, but should beconstrued to include all possible embodiments along with the full scopeof equivalents to which such claims are entitled. Accordingly, theclaims are not limited by the disclosure.

Moreover, the various embodiments described above can be combined toprovide further embodiments. Aspects of the embodiments can be modified,if necessary to employ concepts of the various patents, applications andpublications to provide yet further embodiments.

These and other changes can be made to the embodiments in light of theabove-detailed description. In general, in the following claims, theterms used should not be construed to limit the claims to the specificembodiments disclosed in the specification and the claims, but should beconstrued to include all possible embodiments along with the full scopeof equivalents to which such claims are entitled. Accordingly, theclaims are not limited by the disclosure.

What is claimed is:
 1. An augmented reality (AR) display system fordelivering augmented reality content to a user, comprising: animage-generating source to provide one or more frames of image data; alight modulator to transmit light associated with the one or more framesof image data; a lens assembly comprising first and second transmissiveplates, the first and second transmissive plates each having a firstside and a second side that is opposite to the first side, the firstside being a plano side, and the second side being a shaped side, thesecond side of the first transmissive plate comprising a first surfacesag based at least in part on a cubic function, and the second side ofthe second transmissive plate comprising a second surface sag based atleast in part on an inverse of the cubic function; and a diffractiveoptical element (DOE) to receive the light associated with the one ormore frames of image data and direct the light to the user's eyes, theDOE being disposed between and adjacent to the first side of the firsttransmissive plate and the first side of the second transmissive plate,and wherein the DOE is encoded with refractive lens informationcorresponding to the inverse of the cubic function.
 2. The AR system ofclaim 1, further comprising an actuator to laterally translate the DOErelative to the lens assembly.
 3. The system of claim 2, wherein the DOEis laterally translated in relation to the lens assembly on aframe-to-frame basis.
 4. The system of claim 2, further comprising aneye tracking module to track a vergence of the user's eyes, wherein theDOE is laterally translated relative to the lens assembly based at leastin part on the tracked vergence.
 5. The AR system of claim 2, whereinthe lateral displacement of the DOE causes the light rays emanating fromthe DOE to appear to diverge from a depth plane, wherein the depth planeis not an infinite depth plane.
 6. The AR system of claim 1, wherein thesystem generates collimated light rays associated with virtual contentthat appears to emanate from infinity.
 7. The AR system of claim 1,wherein the second transmissive plate is placed in relation to the firsttransmissive plate with their respective vertices on an optical axissuch that light associated with outside world objects, when viewed bythe user are perceived as having zero optical power.
 8. The AR system ofclaim 1, further comprising another actuator to laterally translate thesecond transmissive plate in relation to the first transmissive plate.9. The AR system of claim 8, wherein the second transmissive plate islaterally offset in a first direction in relation to the firsttransmissive plate such that light associated with outside worldobjects, when viewed by the user, is perceived as having a positiveoptical power.
 10. The AR system of claim 8, wherein the secondtransmissive plate is laterally offset in a second direction in relationto the first transmissive plate such that light associated with outsideworld objects, when viewed by the user, is perceived as having anegative optical power.
 11. The AR system of claim 1, wherein the imagegenerating source delivers the one or more frames of image data in atime-sequential manner.
 12. A method of generating focal planes, themethod comprising: delivering light associated with one or more framesof image data to a diffractive optical element (DOE), the DOE disposedbetween a lens assembly comprising two transmissive plates, each of thetransmissive plates having a first side and a second side that isopposite to the first side, the first side being a plano side, and thesecond side being a shaped side, the second side of the firsttransmissive plate comprising a first surface sag based at least in parton a cubic function, and the second side of the second transmissiveplate comprising a second surface sag based at least in part on aninverse of the cubic function, the DOE being disposed between andadjacent to the first side of the first transmissive plate and the firstside of the second transmissive plate, and wherein the DOE is encodedwith refractive lens information corresponding to the inverse of thecubic function.
 13. The method of claim 12, further comprising:laterally translating the DOE in relation to the first transmissiveplate such that light rays associated with the virtual content deliveredto the DOE diverge at varying angles based at least in part on thelateral translation.
 14. The method of claim 13, wherein the divergentlight rays are perceived by the user as coming from a depth plane otherthan optical infinity.
 15. The method of claim 13, further comprisingtracking a vergence of the user's eye, wherein the DOE is laterallytranslated based at least in part on the tracked vergence of the user'seyes.
 16. The method of claim 12, wherein the second transmissive plateis placed in relation to the DOE and the first transmissive plate suchthat outside world objects, when viewed by the user through the lensassembly and the DOE, are perceived through zero optical power.
 17. Themethod of claim 12, wherein the second transmissive plate is offset in afirst direction in relation to the DOE and the first transmissive platesuch that outside world objects, when viewed by the user through thelens assembly and the DOE are perceived as having a positive opticalpower.
 18. The method of claim 17, wherein the second transmissive plateis offset in a second direction in relation to the DOE and the firsttransmissive plate such that outside world objects, when viewed by theuser through the lens assembly and the DOE are perceived as having anegative optical power.
 19. The method of claim 18, wherein the firstdirection is opposite to the second direction.
 20. The method of claim12, wherein the system generates collimated light rays associated withthe virtual content that appear to emanate from optical infinity. 21.The method of claim 12, further comprising delivering one or more framesof virtual content to the DOE in a time-sequential manner.
 22. Themethod of claim 21, wherein the DOE is laterally translated in relationto the first transmissive plate on a frame-to-frame basis.
 23. Themethod of claim 21, wherein the one or more frames of virtual contentdelivered to the DOE comprise two-dimensional image slices of one ormore three-dimensional objects.